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W. H. FULWEI LER. PROCESS OF RECOVERING BY-PRODUCTS 0F ILLUMINATING GAS.

, APPLICATION FILED SEPT-18.1916.

Patented July 22, 1919.

2 SHEETS-SHEET 1.

driven EM W/TIVESS.

W. H. FULWEILER. PROCESS OF RECOVERING BY-PRODUCTS 0F ILLILMINATING GAS.

APPLICATION FILED SEPTJB. I916 onted J11ly 22, 1919.

SHEET 2.

IA VEWOA 2 SHEETS l i ED STATES WALTER H. FULWEILER, 0F WALLINGFORD, PENNSYLVANIA, ASSIG-NOR '10 UNITED GAS IMPROVEMENT COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A' CORPORA- TION OF PENNSYLVANIA.

PROCESS OF RECOVERING BY-PRODUGTS OF ILLUMINATING-G-AS.

Specification of Letters Patent.

Patented Jul 22, 1919.

Application filed September 18, 1916. Serial No. 120,591.

Gas, of which the following is a specificatio The principal objects of the present inventlon are,

First: To provide for selectively removing or extracting a large percentage of one or a group of the benzol homologue series, such for example as toluol or benzol or xylol, or a combination of them, from illuminating gas, leaving the other member or members of the series and the rest of the normal constituents in the gas;

Second: To do this in such a way that the operation is not complicated by the deposition of water along with the extracted member or members or by the ai ter deposition of naphthalene, and

Third: To do this without unduly diminishing the candle-power of the gas, or otherwise stated, if the candle-power of the gas is diminished more than it is desirable, in such a Way that it can be readily restored. Stated in general terms, the invention comprises the process of selectively removing one or a group of the h drocarbons' of the benzol homologue series om illuminating gas and allowing the rest of the members of the series to remain in the gas, which consists in scrubbing the gas with an appropriate oil pre-saturated'with the hydrocarbon or group of hydrocarbons which is not to be removed from the gas and in substantially the same proportions as they exist in the gas and under appropriate temperature conditions by which the temperature of the gas is raised during the scrubbing operation. The invention fiurther comprises the improvements to be presently described and finally claimed.

Merely for the sake of clearness of description of the invention reference will be made to the accompanying drawings illustrating a type of apparatus appropriate for the practice of the invention and in which Figure 1,.is a'diagrammatic view.

Fig. 2, is a sectional view, drawn to an enlitrged scale, of a part of the apparatus, an

Fig. 3, is a similar View of another part of the apparatus.

In the following description it will be assumed that toluol is to be removed from the gas and that benzol and xylol and the other homologues and unsaturated hydrocarbons are to remain in the same. This assumption is made for the reason that at the present time the demand for toluol is large and because if Xylol or solvent naphtha, as it is sometimes called, is removed from the gas,

it is practically impossible to put it back and the illuminating value of xylol is relatively very large. The assumption is not made by Way of limitation because it is possible to remove xylol or lbenzol instead of toluol and moreover these substances and those of which they are types can be removed singly or in various combinations, leaving the others in the illuminating gas.

It may be said that where, as for example, toluol is to be removed the principle of the invention is to approximately balance the vapor tension of the scrubbing oil that has passed through the scrubber with the vapor tension of the scrubbing oil that is to pass into the scrubber, by adding to the latter benzol and xylol or solvent naphtha and unsaturated hydrocarbons in the same proportions as they exist in the gas, and of course as they exist in the oil that leaves the scrubber. Usually and prior to my invention it was necessary to reduce the temperature of the gas as far as possible, 2'. e to from 75 to 85 F. whereas I am not thus restricted loing operation and I thus avoid the condensation of water which would be admixed with the scrubbing oil, seriously reducing its efiiciency and be troublesome in its removal. Again for this reason I avoid the deposition of naphthalene.

For the sake of a further description I will describe the removal of toluol and Will gas, 'as thecase may be, from which am-' moma and cyanogen have been removed, and from which tar has been extracted and which has been cooled, for example to 100 F., is passed through the scrubber 1, and then by the pipe 2, through the scrubber 3, and off at the off-take 4, at a temperature of 110 F.

The scrubbing oil enters the scrubber 3, by

the pipe 5, at a temperature of from 125 to 145 F. and it leaves the scrubber 3, by the pipe 6, at a temperature of about 95 F. It then passes through the re-heater 7, in which its temperature is raised to about 110 F., through the pump 8, and pipe 9, to the scrubber 1, which it leaves at about 100 F. The scrubbing oil before it enters the scrubber 3, and for example while it is in the pipe 5, is pre sa turated by adding to it, for example by way of the connection 10, benzol and xylol, or solvent naphtha and unsaturated hydrocarbons, in the same proportions as they exist in the gas. These latter substances may be obtained from any appropriate or convenient source preferably as will be later described by fractional distillation of the light oil mixture obtained in the process. The pre-saturated scrubbing oil washes from the gas toluol even to the extent of 95% of the toluol present in the gas.-

The scrubbing oil passing through the pipe 11, and pump 12, therefore contains the toluol which it has washed from the gas and also the xylol or solvent naphtha and benzol and unsaturated hydrocarbons whichwere previously added to it, and the gas leaving the offtake 4, is practically deprived of toluol but contains xylol, benzo-l'and all of the other illuminants. Of course the removal of toluol diminishes the candle-power of the gas but this loss of candle-power, due to the removal of the toluol, may be made up by the addition of appropriate illuminants to the gas, as for instance by-pre-saturating the scrubbing oil with a suflicient excess of for example xylol to restore the illuminating value.

The scrubbing oil' containing the toluol passes through the heater 13, and the steam heater 14, and by way of the pipe 15, to the dephlegmating column 16. The connection 15, whenthe dephlegmating column consists of thirteen sections may enter at about the eighth section from the bottom. 17, are connections for supplying live steam to the steam heater Y14, and to the still 18, of the dephlegmating column. The scrubbing oil passes from thestill 18, by pipe 19, through the heater or heat exchanger 13, b pipe 20, through heater or heat exchanger by pipe tillation is greatly lessened and the scrub- 21, through cooler 22,cooled by waterconnec tions, and thence by pipe 23, and pump 24, to pipe 5, past the connection 10, where the :by-products of the kind recited and which are not to be removed from the gas, are added to it. The temperature of the scrubbing oil leaving the heater 13, is about 175 F., the temperature of the oil leaving the water cooler is from 125 to 145 F. The lighter fractions leave the dephlegmating column by the pipe 2-5, pass through the water cooled condenser 26, and reach the water and oil separator 27 From the oil separator thecondensed va ors, such as toluol, xylol, benzo'l and the oi go by way of the sealed overflow-31, to the oil storage tank 30, and thereafter they are distilled and separated in any appropriate still, not shown. In operating for instance for. the recovery of toluol, the benzol and toluol are distilled off and then the distillation may be discontinued and the benzol, which contains a reater portion of the unsaturated hydrocav us, is added to the residue which consists of xylol and other higher boiling homologues, a certain proportion of the scrubbing oil and unsaturated hydrocarbons, and this mixture is used for pre-saturating the scrubbing oil. In this manner the time and expense of this re-dis bing oil is recovered. Furthermore in this manner the scrubbing oil is presaturated with unsaturated hydrocarbons and thus they are not removed from the gas and lost; this results in a considerable saving in illuminating value. The connections 28 and the pump 29, serve to deliver any uncondensed vapors to the gas leaving the ofitake 4.

Fig. '2, in a very diagrammatic fashion shows the interior construction of one of the scrubbing towers and this interior construction may consist of Wooden grids 32.

Fig. 3, shows diagrammatically the well known interior construction of several section-s of the 'dephlegmating column 16.

It will be obvious to those skilled in the art that the described process may be modified as to details and as to the substances or by-products that are selectively removed from illuminating gas, so that the invention is not limited as to those matters.

What I claim is:

1. The process of manufacturing toluol from illuminating gas which consists in scrubbing it with an appropriate oil presaturated with benzol, xylol and unsaturated hydrocarbons in substantially the same proportions as they exist in the gas and controlling the temperature conditions to raise the temperature of the gas during the scrubbing operation and approximately balance. ing the vapor tension of the scrubbing oil before and after the scrubbing operation.

2. The process of manufacturing toluol from illuminating gas which consists in scrubbing it with appropriate oil pre-satu tension of the scrubbing oil before and after rated with benzol, xylo-l and unsaturated hythe scrubbing operation, and delivering drocarbons in substantially the same p-rofrom the Works gas containing xylol in portions as they exist in the gas, controlling normal quantity and thus preventing the the temperature conditions to raise the temdeposition of naphthalene in crystalline perature of the gas during the scrubbing opform. eration, approximately balancing the vapor WALTER H. FULWEILER. 

